-
CLINICAL CASE
Agnieszka Nęcka1, Janusz Skrzypczyński1, Joanna Antoszewska2
Miniscrew-Anchorage in Treatment of Impacted Second Molar in
Mandible – Case ReportMaksymalne zakotwienie w leczeniu
zatrzymanego drugiego zęba trzonowego w żuchwie – opis przypadku1
Private practice, Dentalux sp. z o.o., Warszawa, Poland 2
Department of Maxillofacial Orthopaedics and Orthodontics, Wroclaw
Medical University, Poland
AbstractPhenomenon of impaction of second molars is a relatively
rare dental anomaly, requiring adequate and sophis-ticated
anchorage unit. This paper presents a case of 15-year-old patient
with severely impacted tooth 47, treated multidisciplinary applying
simultaneous surgical exposure of the second molar, extraction of
the third molar and insertion Absoanchor® miniscrew implants in
retromandibular region as anchorage supporting uprighting of the
impacted molar. During surgery, an 009” ligature wire was extended
from the head of miniscrew above the oral mucosa, enabling future
loading with biomechanically controlled force. The hook-shaped
attachment made of 0.16 × 0.22” stainless steel wire was bonded to
the crown of impacted tooth, with a light-cured composite. After
the week, orthodontic traction was applied: elastic thread
generating force about 50 g. Eventually, second lower molar upright
was efficiently completed in 6 months, revealing the deep caries in
the impacted tooth requiring further treatment. The achieved result
encourages to state, that efficient orthodontic treatment of
impacted and mesially tipped lower molars, conventionally requiring
complex anchorage reinforcement, is apparently facilitated due to
insertion of miniscrews. Ectopic teeth must also not be neglected
concerning generally sound dentition – conse-quently: the whole
organism, since impacted teeth may be affected with severe caries
(Dent. Med. Probl. 2010, 47, 3, 379–383).
Key words: orthodontics, miniscrews, impacted lower molar.
StreszczenieZjawisko zatrzymania drugiego zęba trzonowego jest
stosunkowo rzadką zębową nieprawidłowością wymagającą odpowiedniego
i złożonego zakotwienia. W pracy przedstawiono opis przypadku
15-letniego pacjenta ze skompli-kowanym zatrzymaniem zęba 47.
Przeprowadzono leczenie interdyscyplinarne, jednoczasowo,
odsłaniając drugi ząb trzonowy, usuwając trzeci ząb trzonowy i
wszczepiając miniśrubę Absoanchor® w trójkącie zatrzonowcowym w
celu zakotwienia do pionizacji zatrzymanego zęba trzonowego.
Podczas zabiegu chirurgicznego na powierzchnię błony śluzowej z
główki miniśruby został wyprowadzony drut ligaturowy o przekroju
009” umożliwiający później-sze obciążenie biomechanicznie efektywną
siłą. Zaczep w kształcie haczyka wykonany z drutu stalowego o
prze-kroju 0,16 × 0,22” został przyklejony za pomocą kompozytu
polimeryzowanego światłem do korony zatrzymanego zęba. Po tygodniu
zadziałano siłą nici elastycznej, o wartości około 50 g. Pionizację
drugiego zęba trzonowego w żuchwie zakończono po 6 miesiącach,
stwierdzając głęboką próchnicę w zatrzymanym zębie, wymagającą
dal-szego leczenia. Uzyskany rezultat pozwala stwierdzić, że
skuteczne leczenie zatrzymanych i nachylonych mezjalnie dolnych
zębów trzonowych, wymagające – w tradycyjnej technice –
skomplikowanego wzmocnienia zakotwienia, jest ewidentnie prostsze
dzięki wszczepieniu miniśrub. Takiej ektopii nie można zaniedbać ze
względu na ogólny stan uzębienia, a tym samym całego organizmu,
gdyż zęby zatrzymane mogą być dotknięte ciężką chorobą próch-nicową
(Dent. Med. Probl. 2010, 47, 3, 379–383).
Słowa kluczowe: ortodoncja, miniśruby, zatrzymany dolny ząb
trzonowy.
Dent. Med. Probl. 2010, 47, 3, 379–383 ISSN 1644-387X
© Copyright by Wroclaw Medical University and Polish Dental
Society
Phenomenon of impaction of second molars is a relatively rare
dental anomaly: the prevalence varies from 0.03–2.3% [1–4].
Impacted second
molars in mandible are most commonly mesially inclined, what can
be related to their physiologi-cal development [5]. Initial mesial
axial inclina-
-
A. Nęcka, J. Skrzypczyński, J. Antoszewska380
tion of these tooth buds subject to natural self-correction
mechanism, connected with remod-eling of the the anterior border of
mandibular ramus and mesial migration of the first molar to the
leeway space. Disturbances of this process can lead to persistent
mesial inclination of the second molar and its impaction. Arch
length deficiency and crowding of tooth buds – wisdom tooth or
second premolar – lead to their competition for space with second
molar [6–8]. Space excess in the dental arch is listed as another
etiologic factor of second lower molar impaction. It is also
con-sidered in the literature that developing second molars – for
their normal vertical eruption – need the close guidance of distal
root of the first molar; therefore if the first molar is absent the
second one can become impacted despite greater space available in
the dental arch [7]. Iatrogenic impac-tion of the lower second
molars can occur during orthodontic treatment. Therapeutic
procedures which create mesio-distal force vectors and tip the
mandibular first molars distally, must be ap-plied with particular
cautiousness: orthodontic sagittal expansion, prevention of the
mesial shift of the first permanent molars using lip bumper or
lingual arch. Moreover incorrectly fitted band on the first
permanent molar, especially in the mixed dentition stage, can cause
impaction of second molar [7–9].
Indications for treatment of impacted molars, found in the
literature, are the risk of resorption of the neighboring teeth,
caries and periodontal problems, shortening of the dental arch
perimeter and excessive eruption of opposed teeth [10, 11]. The
optimal patient’s age to treat mandibular im-pacted molars is from
11 to 14 years, when second molar root formation is still
uncompleted [7].
There is no standard solution in treatment of impacted second
molars and management de-pends on several local factors such as the
inclina-tion of the impacted tooth, the position of the third molar
and the degree of teeth crowding or follicle collision. Surgical
exposure of the second molar, with/or without extraction of the
third molar and with/or without luxation of the second molar were
yet the most successful reported protocols re-ported in the
literature [11]. Frequent coexistence of second molar mesial
tipping requires upright-ing mechanics of fixed appliance.
Conventional orthodontic technique requires adequate anchor-age
unit, although undesired extrusion of upright molar is unavoidable.
Furthermore, limited access of the crown of molar being upright
frequently results in imprecise band/bracket placement thus
interfering with planned biomechanics [12]. Re-cently, the
introduction of miniscrews for abso-lute anchorage has changed the
clinical and bio-
mechanical approach to the problem of impacted mandibular second
molars [10, 12–16].
The aim of this paper was to describe the miniscrew-anchorage in
treatment of impacted second molar.
Case ReportA 15-year-old boy was referred to the orthodon-
tist by the dentist after the routine checkup, with diagnosed
absence of second molar in the right part of the mandible.
Evaluation of panoramic radio-graphs, teleradiograms and casts were
performed. Patient presented with skeletal Class I, increased
overjet (3.6 mm) and overbite (4.8 mm) and the mi-nor crowding in
both jaws. The analysis of initial panthomogram (Fig. 1) revealed
crowding of lat-eral lower teeth, root divergence of teeth 42 and
43, mesially tipped and impacted right second molar which was in
close proximity to the wisdom tooth germ. First right lower molar
was tipped distally. On the left side, the mesial impaction of the
third molar was observed, together with infraocclusion and slight
mesial tipping of second left mandibular molar. Treatment plan
called for extraction of the tooth 48, since the attempt to place
it upright might have been burdened with the risk of tooth 47 root
resorption. Furthermore, such extraction created space for
miniscrew implant insertion providing desired force vector:
horizontal with weak vertical component. Simultaneous surgical
exposure of the second right molar, extraction of the third molar
and the miniimplantation (1.3 mm in diameter, 7 mm in length –
Absoanchor®) in retromandibu-lar region took place in the first
stage of treatment. During surgery, an 009” ligature wire was
extended from the head of miniscrew above the oral muco-sa, as the
point of attachment of future force. The crown of the first molar
severely blocked lower right second molar, thus only small distal
portion of its crown was exposed serving as no satisfac-tory
surface for bonding regular bracket or button. The hook-shaped
attachment made of 0.16 × 0.22” stainless steel wire was bonded to
the crown of im-pacted tooth, with a light-cured composite. After
the week, orthodontic traction was applied: elastic thread
generating force about 50 g. Subsequently, after gradual uprighting
the second molar, initial attachment was replaced by regular
lingual button. The elastic thread was changed every month to gain
continuous force. To evaluate the progress of treat-ment periapical
radiographs of second molar were taken after 4 (Fig. 2a) and 6
months (Fig. 2b).
Second mandibular molar uprighting was ef-ficiently completed in
6 months (Fig. 3), however deep dental caries was revealed in this
molar. Its
-
Treatment of Impacted Second Molar in Mandible 381
Fig. 3. Final panthomo-gram
Ryc. 3. Pantomogram końcowy
Fig. 1. Initial panthomogram
Ryc. 1. Pantomogram wyjściowy
Fig. 2a. Periapical radiogram taken 4 months after beginning of
treatment
Ryc. 2a. Radiogram okołowierzchołkowy wykonany 4 miesiące po
rozpoczęciu leczenia
Fig. 2b. Periapical radiogram taken 6 months after beginning of
treatment
Ryc. 2b. Radiogram okołowierzchołkowy wykonany 6 miesięcy po
rozpoczęciu leczenia
-
A. Nęcka, J. Skrzypczyński, J. Antoszewska382
roots must still rotate mesially, nonetheless it re-quires
further treatment stages dependent on pa-tient’s decision.
DiscussionManagement of impacted molars is considered
complex, often requiring a multidisciplinary treat-ment approach
[17]. Numerous, traditional orth-odontic approaches were proposed
in literature for uprighting mesially tipped mandibular sec-ond
molars, however all of them required anterior anchorage [6, 8,
18–24]. Miniscrews as absolute anchorage for uprighting molars,
extended possi-bilities of treatment of impacted molars. There are
two optional methods of anchorage reinforcement for this purpose:
1) direct anchorage enabling pulling bonded attachment on impacted
tooth to-wards miniscrew in retromolar triangle region [10, 12, 13,
16], 2) indirect anchorage enabling repel-ling bonded attachment on
impacted tooth from adjacent one, where the latter is connected
with miniscrew inserted between dental roots [15, 16].
Duration of uprighting second molars is simi-lar in both
methods: from 3–6 months [10, 12, 13, 15, 16].
Direct miniscrew anchorage in treatment mesially impacted molars
has many advantages: eliminates the possibility of unwanted
movement of the anchoring unit, utilizes retromolar region
presenting adequate thickness and high quality of cortical bone for
miniscrew insertion and requires only one miniscrew and a single
attachment: but-ton, bracket, hook [12, 16]. This method has also
some disadvantages: gingival inflammation is sometimes observed
distally to the second molar, around ligature wire although it can
be reduced by proper oral hygiene or medication; effectiveness is
highly diminished if the force span is short. Fur-thermore, this
mechanics is almost inapplicable in upper jaw due to poor bone
quality of maxillary tuberosity [12, 15].
Miniscrews in indirect methods are placed between first molar
and second premolar [15, 16]
and rarely between the mandibular first and sec-ond premolars
[15]. However, for these locations of miniscrews one must consider
the anatomy of inferior alveolar canal, volume of buccal alveo-lar
bone and risk of dental roots damage [25, 26]. Unwanted movement of
the tooth connected with miniscrew is another side effect
accompanying in-direct miniscrew anchorage resulting from either
improper bracket placement or weak connection of the miniscrew and
anchoring tooth [16].
Orthodontic loading in direct anchorage method is recommended to
be applied immediate-ly, after miniscrew placement or after two
weeks of healing and succeeds third molar extraction. As the source
of orthodontic force elastic thread or ni-ti closed spring are
proposed, generating 50–150 g force [10, 12, 13]. In this case
orthodontic traction generating force about 50 g was also efficient
for impacted molar upright achieved within 6 months, using elastic
thread expanded between miniscrew and bonded attachment on molar
occlusal surface. Such result, proving proper application of direct
anchorage in presented case, is in accordance with current
literature reports, thus promoting minis-crews in nowadays
treatment approach.
ConclusionsEfficient orthodontic treatment of impacted
and mesially tipped lower molars, conventionally requiring
complex anchorage reinforcement, is ap-parently facilitated due to
insertion of miniscrews: orthodontic device of 21st century.
Retromolar area presents adequate thickness and high quality of
cortical bone for stable fixation of miniscrew, therefore it may be
routinely considered in treat-ment of lower lateral teeth crowding
related to a second molar impaction.
Concerning deep carious cavities present in impacted molars,
adjacent teeth are also endan-gered, therefore efficient management
of lower impacted molars not only improves occlusion, but is of
certain importance for generally sound denti-tion and –
consequently: the whole organism.
References [1] Farman A.G., Eloff J., Nortje C.J., Joubert J.J.:
Clinical absence of the first and second permanent molars. Br.
J. Orthod. 1978, 5, 93–97. [2] Varpio M., Wellfelt B.: Disturbed
eruption of the lower second molar: clinical apperance, prevalance
and etiol-
ogy. J. Dent. Child. 1988, 68, 173–178. [3] Vedtofte H.,
Andreasen J.O., Kjaer I.: Arrested eruption of the permanent lower
second molar. Eur. J. Orthod.
1999, 21, 31–40. [4] Bondemark L., Tsiopa J.: Prevelance of
ectopic eruption, impaction, retention and agenesis of permanent
second
molars. Angle Orthod. 2007, 77, 773–778. [5] Wellfelt B., Varpio
M.: Disturbed eruption of the permanent lower second molar.
Treatment and results.
J. Dent. Child. 1988, 55, 183–189.
-
Treatment of Impacted Second Molar in Mandible 383
[6] Majourau A., Norton L.A.: Uprighting impacted second molars
with segmented springs. Am. J. Orthod. Dentofac. Orthop. 1995, 107,
235–238.
[7] Shapira Y., Borell G., Nahlieli O., Kuftinec M.M.:
Uprighting mesially impacted mandibular permanent second molars.
Angle Orthod. 1998, 6, 173–178.
[8] Eckhart J.E.: Orthodontic uprighting of horizontally
impacted mandibular second molars. J. Clin. Orthod. 1998, 32,
621–624.
[9] Sawicka M., Racka-Pilszak B., Rosnowska-Mazurkiewicz A.:
Uprighting partially impacted permanent sec-ond molars. Angle
Orthod. 2007, 77, 148–154.
[10] Giancotti A., Arcuri C., Barlattani A.: Treatment of
ectopic mandibular second molar with titanic minis-crews. Am. J.
Orthod. Dentofac. Orthop. 2004, 126, 113–117.
[11] Magnusson C., Kjellberg H.: Impaction and retention of
second molars: diagnosis, treatment and outcome. A retrospective
follow-up study. Angle Orthod. 2009, 79, 422–427.
[12] Park H.S., Kyung H.M., Sung J.H.: A simple method of molar
uprighting with micro-implant anchorage. J. Clin. Orthod. 2002, 36,
592–596.
[13] Giancotti A., Muzzi F., Santini F., Arcuri C.: Miniscrew
treatment of ectopic mandibular molars. J. Clin. Orthod. 2003, 37,
380–383.
[14] Park H.S., Kwon O.W., Sung J.H.: Uprighting second molars
with micro-implant anchorage. J. Clin. Orthod. 2004, 38,
100–103.
[15] Sohn B.W., Choi J.H., Jung S.N., Lim K.S.: Uprighting
Mesially Impacted Second Molars with Minisrews Anchorage. J. Clin.
Orthod. 2007, 41, 94–97.
[16] Lee K.J., Park Y.C., Hwang W.S., Seong E.H.: Uprighting
mandibular second molars with direct miniscrew anchorage. J. Clin.
Orthod. 2007, 41, 627–635.
[17] Bonetti G.A., Pelliccioni G.A., Checchi L.: Management of
bilaterally impacted mandibular second and third molars. JADA 1999,
130, 1190–1194.
[18] Gazit E., Lieberman M.: A mesially impacted mandibular
second molar. Treatment considerations and outcome: a case report.
Am. J. Orthod. Dentofac. Orthop. 1993, 103, 374–376.
[19] Sinha P.K., Nanda R.S., Ghosh J., Bazakidou E.: Uprighting
fully impacted mandibular second molars. J. Clin. Orthod. 1995, 29,
316–318.
[20] Warren D.W.: Correction of impacted mandibular second
molars. J. Clin. Orthod. 1998, 32, 89–90. [21] Park D.K.:
Australian uprighting spring for partially impacted second molars.
J. Clin. Orthod. 1999, 33, 404–405. [22] Resch D.: Clinical
management of unilaterally impacted mandibular first and second
molars. J. Clin. Orthod.
2003, 37, 162–164. [23] Miao Y.Q., Zhong H.: An uprighting
appliance for impacted mandibular second and third molars. J. Clin.
Orthod.
2006, 40, 110–116. [24] Reddy S.K., Uloopi K.S., Vinay C., Subba
Reddy V.V.: Orthodontic uprighting of impacted mandibular
perma-
nent second molar: a case report. J. Indian. Soc. Pedod. Prev.
Dent. 2008, 26, 29–31.[25] Cheng S.J., Tseng I.Y., Lee J.J., Kok
S.H.: A prospective study of the risk factors associated with
failure of mini-
implants used for orthodontic anchorage. Int. J. Oral
Maxillofac. Implants 2004, 19, 100–106.[26] Park H.S., Jeong S.H.,
Kwon O.W.: Factors affecting the clinical success of screw implants
used as orthodontic
anchorage. Am. J. Orthod. Dentofac. Orthop. 2006, 130,
18–25.
Address for correspondence:Agnieszka NęckaDentalux sp. z
o.o.Racławicka 13102-117 Warszawa Polande-mail:
[email protected]
Received: 2.02.2010Revised: 2.08.2010Accepted: 30.08.2010
Praca wpłynęła do Redakcji: 2.02.2010 r.Po recenzji: 2.08.2010
r.Zaakceptowano do druku: 30.08.2010 r.